Process for absorption of carbon dioxide from gases and vapors



I Patented 10, '1-931 l I UNITED STATES PATENT OFFICE JAN AL, AMSTEI BIDAM, NETHERLANDS, ASSIGNOR TO NAAMLOOZE VENNOOTSCHAI' DE BATA-AFSGHE PETROLEUM MAATSCHAPPIJ', OF THE HAGUE, NETHERLANDS I PROCESS FOR ABSORPTION OF CARBON DIOXIDE FROM GASES AND VAPORS No Drawing. Application filed Ilsebruary 20, 1930, Serial No. 430,108, and in the Netherlands February 26, 1929.

My invention relates to a process for the derstood, is of great importance'for the remanufacture of mixtures of gases or vapors actions in que tion. with lower carbon-dioxide content from mix- This problem has now been completel tures of gases or vapors with higher carbonsolved by using fixed alkali-carbonate, and dioxide content and for the absorption of carsteam in excess of equimolecular proportions. hon-dioxide. from gases and vapors; v The following reaction takes place:

Principle of the invention Z eP a1k.2)coa+'H o+co =2(a1k Hc0a+,a cal. plled-to all possible kinds of gases contalnlng K 1 carbonic acid, though the thought underlying 1n Whleh represents an elkelme metalthe invention was more especially the removal The Principle of Process according to of carbon-dioxide from gasmixtures which the inventioeeensists in the g s are obtained from hydrocarbons such as Vapors eontemlng l dlqxlde belng methane by incomplete combustion or conbrought P Contact, together wlth excess of version with steam. T 1 a "steam, .Wlth fi e alkahfcarbonate oreub 5 A method f a f ct i hydro} stances containmgalkall-carbonate at ele: gen consists in the incomplete combustion or 'e temperature ebeve P con'denslng conversion with steam of hydro-carbons. In P i t effsteam and l wlthout e PP bot cases a'mixture is obtained consisting of 0310110 Preesurehy rogen, carbon-monoxide and any non- For KHCO'B the P e of 2 converted hydrocarbon and containing, in T* together at 1100 addition carbon dioxide and water va or. ememets'te about 8 3 'y- At e When the conversion with steam is car ed slght It would: therefore, be expected. that 111 out inxtwot stages when the hydrogen is tlns manner no more 00 could be removed produced by incomplete combustion followed from the ge then p to a 2 r flg by reaction between the CO and steamtoform P Dg C02 pre ure f 4: 9 hydrogen, it is of importance to remove the or about 5% calculated on gas and steam carbondioxide from the gas mixture develtogether. The 00 pressureis determined, foped after the first stage or after the'incomhowever, by the product of P X-P which plete combustion, or at least to keep the per-- at 110 0., expressed in cm. mercury prescentage of CO as low as possible, because sure, is: i i in the further formation of hydrogen from 8 8 CO and steam, CO is formed. p k 'l-fi,

I CH4+QHZO=COZ+4HZ Beginning? for instance, with 1 velume' A CO+H2O CO2+H 2 part CO and 2 volume parts steam, thus so that 'in order to displace the equilibrium' a two-fold excess of steam, when volume of reaction to theright itis essential that the part CO is absorbed there. willstill be 1% CO already present is made as low as posvolume parts steam, thus a three-fold exsible. I cess of steam. In other words, as CO is re- Seeing that in both cases steam is already moved from the gas 'mixt r S0 t EX E present in the gas mixture a method has been of steam "becomes greater. Consequently sought 'for the reinovalof carbon dioxide when almost all the CO has been absorbedr whichcanbe carried out without condensing and the quantity of steam is say atmos- 45 the steam, awcondition which, as will be unphere, or about 19 cm, mercury pressure,

' cess takes place more slowly.

removed from a gas mixture and application in practice has shown this indeed to be the case.

. E mample A tube is charged with potassium carbonate precipitated on pumice stone (made by adding pumice stone to an a ueous solution of K 00 and then drying. y evaporation) or with a mass obtained by mixing for instance pumice stone and the like with' pulverulent carbonate. The mass put into the tube weighs 66.5 grammes and contains about 16 grammes K CO This mass iskept at a temperature of 110 C. or higher while a gas containing 17% CO (calculated on dry gas) is conducted through it after previously being passed through boiling or practically boiling water. When the gas is passed through the tube at higher speeds it is found that the temperature of the absorbent mass is increased by, th heat developed in the reaction.

S d at Tempera- Per cent ture of abg g 00: after m sls lh tlie the 28 1 0313321 -tubeln0. 233, 3 on dry was 110-115 6 Traces. 115-118 10 Traces.

As soon'as the quantity of carbon dioxide approaches the theoretically possible limit the CO passes through without being absorbed, but before this occurs practically all the CO is absorbed, as a pears from the figures given above. .The a kali-bicarbonate can be regenerated in various ways, for instance by; applying a vacuum at elevated temperature or by passing through a current.

of air. Regeneration can be effected very quickly according tothe invention by conducting through the mass at elevated temperature (dried) ammonia gas, whereby principally the following reaction takes place:

In this manner at a temperature of about 180 C. the KHCO can be very quickly regenerated;, at lower temperatures the pro- If, for some reason or other it is hot desired or' it is impossible to 'useammonia for this purpose, then it is recommendable to carry out the regeneration at a somewhat higher temperature, s'ay 220 0., by conducting through air or some; other suitable inert gas or vapor, or by applying a vacuum, or by using a combination of these methods.

Instead of potassium carbonate also other other carriers-than pumice stone, or mixed" with other substances. Further it is recommended to finely distribute the alkali-care bonate in some way or other.

As remarked above, the method described is particularly of importance for the removal of CO from gas mixtures which contain an excess of steam and which have to be further converted with steam after the absorption, and whereby the steam, therefore, need not be condensed, such as is the case in washings under pressure, and in washings with solutions.

Another important advantage attached to the process according to the invention lies in the fact that-no valuable components of the gases are assimilated in the absorbing mass, whilst for instance in pressure-washings of gas mixtures containing hydrogen, carbon monoxide and carbon dioxides up to 10% of the hydrogen present is removed from the mixture. Another fact of importance is that with an increasing steam content the rateof the CO absorption also increases, thereby making it possible to adjust the rate of absorption as desired.

Further there is an advantage in the fact that the absorption, can be carried out at relatively low temperatures, which from a point of view of economy is in some cases of great importance. In this cbnnection it is likewise an advantage of the process according to the invention that the temperatures for absorption andfor regeneration .lie close together. i 1

What I claim is':'

1. The process for absorbing carbon dioxide from gases. containing the same, comprising treating the gas in the'presence of a solid alkali carbonate and at a temperature above the condensing temperature of steam, with steam in excess of the equimolecular quantity with respect, to the carbon dioxide content of the gas. r

'2. The process for absorbing carbon dioxide from gases containing the same, comprising passmgthe gas together with steam in excess of the e uimol ec'ular quantity with respect to the car 11 dioxide cohtent oi the gas through a mass containing finely distributed alkali carbonate, the temperature each volume of carbon dioxide to be abbeing maintained above the condensation sorbed. k i temperature of steam. In testimony whereof, I have aflix'ed my 3. The process for absorbing carbon disignature. 5 oxide from gases containing the same, com- JAN AL.

prising treating the gas in the presence of a solid alkali carbonate, at super atmospheric pressure and at a temperature above the condensing temperature of steam, with steam in excess of the equimolecular quantity with respect to the carbon dioxide content of the 4. The process for absorbing carbon dioxide from gases containing the same, comprising treating the gas in the presence/of a o solid alkali carbonate and at a. temperature above the condensing temperature of steam, with steam in excess of the equimolecular quantity with respect to the carbon dioxide 0 content of the gas, and regenerating the alkali by subjecting it to gaseous ammonia at about 180 C. a

5. The process for absorbing carbon dioxide from gases containing the same, com- 7 prising treating the gas in the presence of a solid alkali carbonate and at a temperatureabove' the condensing temperature of steam, with steam in excess of the equimolecular quantity with respect to the carbon dioxide 0 content of the gas, and regenerating the alkali by, heating to about 220 C. and applying a vacuum.

6. The process for absorbing carbon dioxide from gases containing the same, comprising treating the gas in the presence of a- 1% solid alkali carbonate and at a temperature above the condensing temperature of steam, with steam in excess ofthe equimolecular quantity with respect to the carbon dioxide content of the gas, and regenerating the alv kali by heating and passing an inert gas through the same. Y

7. The process for absorbing carbon dioxide from gases containing the same, comprising treating the gas in the presence of solid potassium carbonate and at a tempe rature above the condensing temperature of steamwith steam in excess of the equi-i 0 molecular quantity with respect to the carbon dioxide content of the'gas.

8. The'process for absorbing carbon dioxide from gases containing the same, comprising treating the gas in the presence of 55 solid sodium carbonate under super atmospheric pressure and at a temperature above the condensing temperature of steam, with steam in excess of the equimolecular quantity with respect to the carbon dioxide con- 00 tent of the gas. 15"

9. The process for absorbing carbon dioxide from gases containing the same, comprising treating the gas in the presence ofa solid alkali carbonate at a temperature of at 65 least 110 Cuwith two'volumes of steam for i 133 

